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SiteCheck Web Intel – Unpaywall Open-Access Lookup
x402
SiteCheck Web Intel – Unpaywall Open-Access Lookup is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).
Looks up open-access status and best free full-text link for a paper by DOI using the Unpaywall API
Price / call$0.002
Success—
StatusUnknown
How this service works
Unpaywall open-access lookup by DOI (free API; it requires a contact e-mail set in UNPAYWALL_EMAIL, not a key): is the paper open access, OA status, best free full-text link, journal and publisher. Returns metadata and links only, not the PDF.
Output
Returns metadata about the paper identified by the DOI: whether it is open access, the OA type/status (e.g. gold, green, hybrid), the best available free full-text URL, journal name, and publisher. Does not return the PDF itself, only links and metadata.
Example use cases
Verify open access before paywalling
“I'm trying to read the paper with DOI 10.1016/j.cell.2021.01.001 — is it available for free somewhere, or do I need institutional access?”
Enrich citation list with free links
“I have a list of DOIs from my literature review. Start with 10.1126/science.abb2507 — is it open access, and what's the direct free full-text URL if one exists?”
Check journal OA policy for a paper
“For the paper DOI 10.1056/NEJMoa2001017, tell me its open access status, which journal published it, and who the publisher is.”
Technical details
Endpoint
GEThttps://api.webintel-api.workers.dev/api/search/unpaywall?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to quickly determine whether a specific academic paper (identified by DOI) is freely readable online, and to get the canonical best free full-text URL. Ideal for literature review workflows, citation enrichment, or helping users avoid paywalls. Prefer this over general web search when you have a precise DOI and need structured, reliable OA metadata rather than guessing from search results.
Side effects
- DOI not found in Unpaywall database — returns null or empty OA data
- Invalid or malformed DOI format causes lookup failure
- Paper exists but has no open access version — returns OA status as false with no free link
- Upstream Unpaywall API downtime causes request failure
- Missing or invalid UNPAYWALL_EMAIL configuration on the server side causes rejection
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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